Protective members such as helmets have been worn to protect a user from head injuries. Protective helmets have been used for many endeavors, including for participants in sports (e.g., football, baseball, lacrosse, racing, cycling, skiing), for commercial activities (e.g., construction) and for military personnel (e.g., pilots, soldiers). Prior art helmets have generally comprised a single layer which is rigidly secured to the head of a user.
U.S. Pat. No. 4,287,613, entitled “Headgear With Energy Absorbing and Sizing Means” disclosed a headgear of the type used by football players. The headgear included a web suspension means comprising looped straps held together by a cord that threads through the looped straps and is knotted. The web suspension means performed a sizing function and maintained the top of the wearer's head out of contact with the upper wall of the helmet shell. The ends of the straps were connected to an encircling band that was fastened at selected locations to the helmet shell.
U.S. Pat. No. 5,035,009, entitled “Protective Helmet and Liner” disclosed a protective helmet having a sheet of sound deadening material between impact force absorbing pad structures disposed on the interior of the protective helmet.
In United States Patent Application 2010/0101005a protective helmet is disclosed that affords guided movement of an inner shell 100 within an outer shell 101 by use of two or more rigid connecting protrusions 103 disposed within slots 102.
United States Patent Application 2013/0205480 discloses a protective helmet which includes a motion restrictor device.
Recent advances in helmets include U.S. Pat. No. 6,826,509, entitled “System And Method For Measuring The Linear And Rotational Acceleration Of A Body Part.” The '509 patent discloses a system using accelerometers to collect, record and process head acceleration data. See FIG. 7 of the '509 patent. See also the related U.S. Pat. No. 7,526,389.
U.S. Pat. No. 7,954,177 entitled “Sports Helmet” disclosed a sports helmet having ear flaps and jaw flaps.
Helmets are designed to prevent or reduce concussions in users, such as athletes. Concussions can have immediate and long term effects. Immediate effects can include dizziness, confusion, nausea, loss of consciousness and difficulty seeing and hearing. Athletes suffering concussions have been diagnosed, including after their deaths, with chronic traumatic encephalopathy (“CTE”). The study of CTE indicates that the condition is related to the behavior of a brain protein called tau. Concussions may cause diffuse axonal injury (“DAI”). Axons connect brain neurons together and allow them to communicate with another. Acceleration of the brain can apparently cause injury to axons. Cerebrospinal fluid (“CSF”) is also implicated in the mechanism of brain injuries. CSF is more dense as compared to brain tissue. The movement of CSF during an impact may affect the amount and location of injury to brain tissue. Injuries to the brain resulting from impacts are referred to a coup and countrecoup injuries. Coup is a French word meaning blow or impact. Countre is a French word meaning opposite. Thus a coup injury occurs on the side of the brain facing the impact; whereas a countrecoup injury occurs on the opposite side of the brain from the impact.